Norwich scientists have made a leap forward in answering an unlikely question with critical importance for our countryside... what are bees’ favourite flowers?

Norwich scientists at the Earlham Institute and UEA have pioneered a new method to analyse which pollen sources are preferred by bees. Pictured: PhD student Ned Peel of the Leggett Group, Earlham Institute. Picture: Earlham Institute

Although it is easy to take these industrious insects for granted they have vast importance to our ecosystems and economy, with a third of our food dependant on their pollination services, estimated to be worth £690m per year to the UK economy.

Understanding a bee's preferred sources of pollen could give valuable information to the farmers who rely on them, and the conservationists trying to save them.

So the Norwich-based Earlham Institute (EI), in partnership with the University of East Anglia (UEA), has developed a new method to rapidly analyse pollen - collected from bees netted in the field - to discover which plants and flowers they originate from.

Norwich scientists at the Earlham Institute and UEA have pioneered a new method to analyse which pollen sources are preferred by bees. Pictured: The MinION portable DNA sequencer from Oxford Nanopore Technologies. Picture: Dr Richard Leggett, Earlham Institute

Rather than relying on time-consuming analysis of pollen grains under a microscope, the new method uses "reverse metagenomics" to identify the plants which individual bees have visited, using a portable DNA sequencer called the MinION.

Dr Richard Leggett, group leader at EI, said the speed of this on-site analysis could boost understanding of where bees look for pollen, which could inform decisions on the correct wildflowers to plant on arable field margins, and tell farmers if pollinators are visiting the plants they need them to.

Ned Peel, a PhD student who carried out the research at EI, added: "Importantly, from a mixed sample of pollen, as well as being able to work out what species of plant bees have visited, we can also measure the relative quantities of each type of pollen. This type of analysis can be applied not only to conserving pollinators but to helping us to sustainably improve crop production that relies on pollinators."

Norwich scientists at the Earlham Institute and UEA have pioneered a new method to analyse which pollen sources are preferred by bees.

Prof Douglas Yu from UEA's School of Biological Sciences, had the initial idea for the project. He found that mixed pollen samples could be analysed against quickly-sequenced "reference skims" of genetic code, rather than the entire genome of the plant.

"In standard metagenomics, short stretches of DNA from mixed samples are compared to whole genomes, which can be expensive to generate," he said. "We discovered that we could conduct the analysis using 'reference skims' instead.

"To make a reference skim, we carry out really cheap sequencing that only needs to partially cover the complete genome of the plant and does not need to be assembled."

The study was published in the journal Methods in Ecology and Evolution.

Scientists said the sample size of 48 bees, studied on part of Pensthorpe Natural Park near Fakenham, was too small to draw meaningful conclusions so far - but having demonstrated a cheap, reliable method of quantifying bee pollen they now hope ecologists can take up the method and apply it more widely.

They said the reverse metagenomics principle can also show how certain wildflowers compete with agricultural flowers for pollinators, or assess the behaviour of pollinators across large areas and land types.

The Earlham Institute plans to carry out more public engagement work around bees and pollinators at the Norwich Science Festival from October 18-26.

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